Ultra high frequency surface acoustic waves enabled Electrode-free digital microfluidic chip

Digital microfluidics has become an indispensable tool for biomedical research involving lab miniaturization and automation, which can realize the programmable manipulation of small droplets. In this paper, an acoustofluidic mechanism for programmable manipulation of small droplets is reported. A square array of interdigital transducers working at about 312 MHZ is fabricated on aluminum nitride piezoelectric film, which are used as sound source to generate surface acoustic waves to pump small droplets in the orthogonal directions. At the same time, the concentration of micron particles in droplets can also be realized for the ultra-high frequency surface acoustic waves. The manipulation of droplets and concentration and mixing of micron particles in droplets can be achieved by controlling of the signal power with the advantage of controlled in the way of programming, high frequency and without complex electrode arrangement, which provides an integrated microfluidics system for droplets manipulation and micron particles concentration.